2014–16 El Niño event

The SST Anomalies Average for 11 October 2015 to 7 November 2015

The 2014–16 El Niño is an ongoing warming of the eastern equatorial Pacific Ocean, that has resulted in unusually warm waters developing between the coast of South America and the International Date Line. These unusually warm waters are influencing the world's weather, with more tropical cyclones occurring in the Pacific Ocean and less in the Atlantic Ocean.

Meteorological progression

The 1997–98 El Niño event was regarded as one of the most powerful El Niño-Southern Oscillation events in recorded history, which resulted in widespread drought, flooding and other natural disasters across the globe. Afterwards the climate of the Pacific Ocean was dominated, by a cool phase of the Pacific decadal oscillation, with three significant La Niña events occurring between 1998–2001, 2007–09 and 2010-12.^[1][2][3] Despite the La Niña background to the Pacific Climate, four El Niño events occurred during 2002–03, 2004–05, 2006–07, and 2009–10, but each was weaker and had shorter impacts than the 1997-98 event.^[2][4] After the 2010–12 La Niña event had ended, near-neutral conditions persisted over the Pacific Ocean with no La Niña or El Niño events occurring.^[5] An intense burst of typhoon activity subsequently took place between September and November 2013, which was thought to have possibly been a precursor signal to an impending change of state of the El Niño Southern Oscillation.^[2]

Between January and April 2014, the climate of the Pacific Ocean started to exhibit features, which suggested to meteorologists, the impending onset of an El Niño event.^[6] Over the ocean, these features included: a rapid fall of the sea level in western Micronesia, as well as a large area of enhanced sea surface temperatures, at low latitudes near the International Date Line.^[2] In the atmosphere these features included persistent westerly winds at equatorial latitudes, which were displaced eastwards towards the Marshall Islands.^[2] A large area of atmospheric convection at a low latitude near the International Dateline, in association with the development, of an unusual amount of early season tropical cyclones near the Marshall Islands.^[2] After surveying various climate models, the World Meteorological Organization started to warn during January 2014, that there was an enhanced possibility of a weak El Niño event happening during 2014.^[7] As a result of some of these conditions, an El Niño Watch was issued by the International Research Institute for Climate and Society and the United States Climate Prediction Center during March 2014.^[8][9]

During May and June 2014, the atmosphere failed to respond in order to reinforce the developing El Niño, with the monsoon trough being weak, tropical cyclone activity slowing, while no episodes of strong westerly winds at a low latitude occurred.^[6] Some of the oceanic indicators of El Niño also did not develop or advance further, with a cooling of sea and sub surface temperatures over the tropical Pacific occurring.^[6][10]

In December 2014, the Japan Meteorological Agency declared the onset of El Niño conditions, as warmer than normal sea surface temperatures were measured over the Pacific, albeit citing the lack of atmospheric conditions related to the event.^[11][12] By January 2015, westerly wind burst activity starting picking up again. The first Kelvin wave developed around March and another formed around May. In addition, another strong westerly wind burst event took place around July in result from twin cyclones between the equator. An even stronger event in October, and an ongoing unusually stronger event during late December 2015 into January 2016, also as a result from twin cyclones from either side of the equator. March and May 2015 both NOAA's Climate Prediction Center (CPC) and the Australian Bureau of Meteorology respectively confirmed the arrival of weak El Niño conditions.^[13][14] El Niño conditions were forecast in July to intensify into strong conditions by fall and winter of 2015.^[15][16] In July the NOAA CPC expected a greater than 90% chance that El Niño would continue through the 2015-2016 winter and more than 80% chance to last into the 2016 spring. In addition to the warmer than normal waters generated by the El Niño conditions, the Pacific Decadal Oscillation was also creating persistently higher than normal sea surface temperatures in the northeastern Pacific.^[17][18] In August, the NOAA CPC predicted that the 2015 El Niño "could be among the strongest in the historical record dating back to 1950."^[19] In mid November, NOAA reported that the temperature anomaly in the Niño 3.4 region for the 3 month average from August to October 2015 was the 2nd warmest on record with only 1997 warmer.^[20]

In August 2015, the CPC reported that this year's El Niño as one of the strongest on record.^[21] August 2015 monthly sea-surface temperature anomalies in the Niño 3.4 region already nudged slightly ahead of 1997 values for the warmest in the modern era.^[22]

In January 2016, NOAA noted that the 3 month average from October to December 2015 tied 1997 for the strongest El Niño event reading on record.^[23][24]

Effects on tropical cyclone activity

The 2014–16 El Niño event influenced the tropical cyclone activity within the Atlantic Ocean by producing strong vertical wind shear, increased atmospheric stability, stronger sinking motion and drier air across the tropical Atlantic.^[25] The El Niño event also influenced activity within the Pacific Ocean, with the Central Pacific basin having its most active tropical cyclone season on record with 16 tropical cyclones recorded during 2015.^[25][26]

Impacts

As the El Niño conditions started to develop during early 2014 sea levels in western Micronesia including in waters surrounding Palau and Guam dropped by 6–9 feet (1.8–2.7 m).^[2]

The severe reduction in rainfall lead to many livestock deaths in the Free State province of South Africa. It is also having an adverse effect on maize production in South Africa as the region is one of the country's leading maize producers.

The 2014–2016 El Niño was expected to be as serious as the 1997–1998 El Niño in New Zealand, with drier weather in summer, a cooler winter and a stormy and windy spring. Agriculture will be significantly affected, with rainfall reduced by 15% on the West Coast of both islands, and increased on the East Coast.^[27][28][29]

In January 2016, Pacifica, California declared a local emergency after El Niño storms damaged the coastline and bluff, forcing residents of the nearby apartment to evacuate due to the crumbling cliffside.^[30]

References